Two agents which have found use recently in clinical practice as histamine H.sub.2 -antagonists are cimetidine (U.S. Pat. No. 3,950,333) and ranitidine (U.S. Pat. No. 4,128,658), the compounds having the following chemical formulae: ##STR1##
In addition, certain chemical substances are valuable as antiulcer agents in mammals by virtue of their so-called cytoprotective activity. These agents can be recognized by their ability to inhibit the formation of gastric ulcers in rats which have been dosed orally with large amounts of ethanol.
U.S. Pat. Nos. 4,374,843 and 4,435,396 disclose 2-guanidino-4-heteroarylthiazole compounds having antiulcer activity.